1. Field of the Invention
The present invention relates to sample warming techniques and devices, and more particularly, to a sample warming device and method useful in transporting samples from natural gas pipelines and the like.
2. Description of the Related Art
Natural gas flowing through pipelines often needs to be sampled to determine its average heat of combustion, and therefore its value as fuel. To take these samples technicians must often drive to remote locations with the sample cylinder exposed to the elements. This results in the sample cylinders equilibrating to ambient temperature, which in winter can easily be below 30.degree. F. Taking a sample under these conditions exposes natural gas from an underground pipeline at approximately 60.degree. F. to a temperature below the boiling point of some components of the sample at the pressure of the pipeline. As a consequence, some components of the natural gas condense to a liquid in the sample cylinder, skewing the composition of the gas phase. Analysis of the head space then fails to give an accurate analysis of the natural gas sample unless the sample cylinder is warmed enough to vaporize any liquefied components, a time-consuming task ill-suited to the analytical laboratory.
Previous attempts to solve this problem in the laboratory (is this correct?) have entailed heating sample cylinders by electrical means. This solution impractical during sample cylinder transport to and from remote field sites, where electricity is unavailable. Heating under these conditions would necessitate wiring trucks especially for this purpose, and would also involve a power drain on the battery whenever the engine is shut off. Consequently electrical heating is unsatisfactory as a solution to this problem.
Thus a need exists for a means of warming sample cylinders during transport to and from remote sites without use of electricity.